Origen

The Old English word cloud was first used to refer to a mass of rock or earth, and is probably related to clot (Old English). Only around the end of the 13th century did the meaning ‘visible mass of condensed watery vapour’ develop, presumably because people could see a resemblance in shape between a cloud and rocks.

On cloud nine you are extremely happy. A possible source of the expression is the classification of clouds given in a meteorological guide published in 1896 called the International Cloud Atlas. According to this guide there are ten basic types of cloud, cumulonimbus being the one numbered nine. Cumulonimbus clouds are the ones that form a towering fluffy mass. They get their name from Latin cumulus ‘a heap’ found also in accumulate (Late Middle English). ‘Cloud nine’ is said to have been popularized by the Johnny Dollar radio show in the USA during the 1950s. Johnny Dollar was a fictional insurance investigator who got into a lot of scrapes. Every time he was knocked unconscious he was taken to ‘cloud nine’, where he recovered. Cloud cuckoo land is a translation of Greek Nephelokokkugia (from nephelē ‘cloud’ and kokkux ‘cuckoo’). This was the name the ancient Greek dramatist Aristophanes gave to the city built by the birds in his comedy The Birds. According to the proverb every cloud has a silver lining, even the gloomiest outlook contains some hopeful or consoling aspect. The saying is recorded from the 19th century, though John Milton expresses a similar sentiment in Comus in 1643: ‘Was I deceiv'd or did a sable cloud / Turn forth her silver lining on the night?’